Re: Voltage drop in DX Power to K3

Posted by N4ZR on Apr 26, 2020; 4:34pm
URL: http://elecraft.85.s1.nabble.com/Voltage-drop-in-DX-Power-to-K3-tp7660188p7660197.html

Aside from  my decimal point problems....  The cable measured 0.3 ohms,
with my DMM, but in retrospect, its measurement could not have been
correct. However, the measurement on the 4005i is about right, because
that was done by comparing the voltages at its input and output, and was
at 100 watts key-down. The 4005i's *voltage drop* at 100 watts was 0.08
*volts*, which strikes me as not bad at all.

73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
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On 4/26/2020 12:11 PM, Bob McGraw K4TAX wrote:

> The power cable at 0.03 ohms on each side,  a total of 0.06 ohms
> resistance.  The 4005i, per his measurements, has 0.08 ohms
> resistance.   The power distribution strip contributes more than 50%
> of the voltage drop.   Actually more than the power cables.
>
> The power cable contributes  1.2 volts of drop.   The 4005i
> contributes an added 1.6 volts of drop for a total of 2.8 volts.
>
> The calculation is simple:    E = I x R      current multiplied by
> amps equal voltage.
>
> 73
>
> Bob, K4TAX
>
>
>
> On 4/26/2020 10:53 AM, Leroy Buller wrote:
>> 40 inches of power cable.  In my experiences,  that could be an issue
>> depending on the gauge of the wire.  I used a long cable 12 gauge and
>> had
>> issues.  Went to 24 inches number 10 gauge and voltage drop
>> significantly
>> improved.  The resustace does not have to be large to cause a
>> voltage  drop
>>
>> Lee
>>
>> On Sun, Apr 26, 2020, 9:47 AM N4ZR <[hidden email]> wrote:
>>
>>> I've had an e-mail exchange with West Mountain Radio.  Measured the
>>> voltage drop inside the 4005i at only .08 volts at 100 watts key down.
>>> My power cable from the 4500i to the K3 measures 0.3 ohms on each
>>> conductor, which at 20 amps should only yield a 1.2 volt drop,
>>> right?  I
>>> don't know where the other volt plus of drop is coming from. The cable
>>> is 40 inches long, and only minor shortening is possible.  It is about
>>> the largest wire that will fit in the Powerpoles on both the K3 and the
>>> 4005i.
>>>
>>> Suggestions welcome
>>>
>>> --
>>> 73, Pete N4ZR
>>> Check out the Reverse Beacon Network
>>> at <http://reversebeacon.net>, now
>>> spotting RTTY activity worldwide.
>>> For spots, please use your favorite
>>> "retail" DX cluster.
>>>
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